Development of a novel Fe@urea nanocomposite for effective harvesting of high lutein-producing microalgae biomass

An Innovative microalgae biomass harvesting is addressed through a newly developed Fe@urea nanocomposite (NC) with high lutein and lipid content. The persistent challenge of scaling up microalgae harvesting for largescale commercial production is undertaken by coating Fe3O4 nanoparticles (NPs) with urea, significantly enhancing biomass harvesting efficiency. This improvement aligns with increased NH2+ groups on the NC's surface, demonstrating superior performance compared to conventional Fe3O4 NPs, especially at pH 4. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fouriertransform infrared spectroscopy (FTIR), and zeta potential analysis validate the efficacy of the Fe@urea NC. The elemental composition was analyzed through energy-dispersive X-ray spectroscopy (EDX) to confirm effective urea coating on the NC surface. Remarkably, enhanced Fe@urea-mediated harvesting within one minute is achieved through NH2+-assisted interactions. Optimization experiments varying NC concentrations and culture pH, guided by the Langmuir model, showcase the NC's multifaceted solution, excelling under a magnetic field and also via self-flocculation. Cell viability tests confirm lutein-enriched microalgae cell integrity during harvesting at pH 4, preventing product leaching. This synthesized Fe@urea NC presents an efficient and viable method for microalgae harvesting, holding promising implications for large-scale microalgae biorefinery applications.